We analyze statistical fluctuations in the pulse-to-pulse spatial fluence distribution of a highly multimode F2 laser beam and the influence that coherence effects have on the attainable smoothness of an ablated surface. The magnitude of fluctuations is predicted to be a few percent, with associated roughness increasing as m½, where m is the number of ablation pulses. By use of a white-light optical interferometer, measurements have been made of roughness induced on N-BK7 glass surfaces ablated with a 157-nm laser, and reasonable agreement with predictions based on this roughening mechanism has been found.
© 2005 Optical Society of America
P. E. Dyer, C. D. Walton, and K. A. Akeel, "Coherence effects in surface roughness induced by vacuum ultraviolet F2 laser ablation," Opt. Lett. 30, 1336-1338 (2005)